@misc{cryptoeprint:2009:221,
author = {David Jao and Kayo Yoshida},
title = {Boneh-Boyen signatures and the Strong Diffie-Hellman problem},
howpublished = {Cryptology ePrint Archive, Report 2009/221},
year = {2009},
note = {\url{http://eprint.iacr.org/}},
}
You will need the url.sty package (comes with most LaTeX installations) for the last line. Otherwise, remove the \url command.